Compaction of prepreg plies on composite laminate structures

Abstract

A flexible compaction sheet is used to compact uncured composite plies onto the surface of a ply layup. The compaction sheet includes a peripheral seal that seals the perimeter of the sheet to the surface of the part layup and forms a vacuum chamber over the plies which is evacuated through the sheet to apply compaction pressure to the plies.

1. A method of compacting an uncured composite layup against a surface of a composite ply layup, comprising:
 positioning the uncured layup between a surface of the ply layup and a gas impermeable sheet, the sheet including a breather network positioned substantially flush with a bottom face of the sheet, said bottom face of the sheet positioned beneath a vacuum plate; 
 forming a gas impermeable seal between the sheet and the surface of the ply layup; and 
 using the sheet to compact the uncured layup by generating vacuum pressure between the sheet and the surface of the ply layup by drawing the vacuum though said vacuum plate comprising a plurality of spatially distributed passageways extending through a bottom face of said vacuum plate, the bottom face of the vacuum plate facing said uncured layup. 
 
     
     
       2. The method of  claim 1 , further including allowing the sheet to flex as the sheet compacts the uncured layup; wherein the breather network is positioned to allow a more uniform application of vacuum pressure to uncured plies during a compaction process. 
     
     
       3. The method of  claim 1 , wherein positioning the uncured layup between the surface of the ply layup and the sheet is performed by:
 placing the uncured layup on the surface of the ply layup, and 
 then placing the sheet over the uncured layup. 
 
     
     
       4. The method of  claim 1 , wherein positioning the uncured layup between the surface of the ply layup and the sheet is performed by:
 holding the uncured layup on the sheet, and 
 then using the sheet to place the uncured layup on the surface of the ply layup. 
 
     
     
       5. The method of  claim 4 , wherein holding the uncured layup on the sheet is performed using a vacuum pressure. 
     
     
       6. The method of  claim 1 , wherein generating the vacuum pressure includes drawing gas through the sheet. 
     
     
       7. The method of  claim 1 , wherein forming a gas impermeable seal is performed by bringing a seal on the sheet into contact with the surface of the ply layup. 
     
     
       8. The method of  claim 1 , wherein said passageways are disposed substantially normal to the surface of the ply layup. 
     
     
       9. A method of installing an uncured composite layup on a surface of a composite aircraft part layup, comprising:
 providing a flexible sheet; 
 applying a vacuum through the sheet; said sheet including a breather network positioned substantially flush with a bottom face of said sheet, said bottom face of the sheet positioned beneath a vacuum plate; 
 using the vacuum applied through the sheet to hold the uncured layup on the sheet; 
 using the sheet to locate and place the uncured layup on the surface of the part layup; 
 forming a vacuum chamber between the sheet and the surface of the part layup and surrounding the uncured layup, including forming a vacuum tight seal between the sheet and the surface of the part layup; 
 drawing a vacuum within the vacuum chamber by evacuating gas within the vacuum chamber through the sheet, the vacuum drawn through said vacuum plate, said vacuum plate comprising a plurality of spatially distributed passageways extending through a bottom face of said vacuum plate, the bottom face of the vacuum plate facing said uncured layup; and, 
 using the vacuum in the vacuum chamber to compact the uncured layup against the part layup. 
 
     
     
       10. The method of  claim 9 , wherein said passageways are disposed substantially normal to the surface of the part layup; and wherein the breather network is positioned to allow a more uniform application of vacuum pressure to uncured plies during a compaction process.